The dynamic range of a system can be defined as the ratio of a specified maximum level of a parameter, such as power, current, voltage, or frequency, to the minimum measurable value of that parameter.
In a signal processing system, this dynamic range can be determined by: (1) analog front end hardware (e.g., the noise figure of the amplification, bandwidth, clip level etc. of the amplifiers, filters and other front end circuit components; and/or ADC (analog-to-digital converter) (e.g., the number of bits, SINAD, reference voltages etc. for the ADC). If a signal is sent into the hardware with a level greater than the maximum input level of the amplifiers or the reference maximum levels of the ADC, the digitized signal will show clipping, wrapping, or both, all of which are unfavorable. Higher dynamic range can be achieved by utilizing higher quality amplifiers and ADCs, etc., but ADCs with more bits of resolution come at a higher cost.
Another mechanism to mitigate the clipping and wrapping effects is to employ what is called a compandor, which uses a non-linear transfer function to dynamically scale the amplitude of input signals to avoid the input signal from approaching the extremes of the dynamic range. The compandor, however, cannot be used in certain applications because it distorts the response of the signals being measured with its non-linear function.
Digital spectrum analyzers work by sampling an input voltage (which may be down converted using various mixing techniques) at a particular rate using an ADC (typically, 16-bit). The digitized data can be converted to the frequency domain using a Fourier transform. To measure lower amplitude signals, the reference level of the spectrum analyzer is adjusted, and thus, the amplifier gain is changed. The maximum level that can be measured at this reference level setting is determined by the bit resolution of the ADC. If during the sampling period a signal with amplitude larger than the maximum level was received even for a brief instant, the Fourier transform calculated will be heavily distorted.
A practical application where this type of limitation can be seen is in the continuous noise based disaggregation methods. In some examples, the continuous noise based disaggregation method can focus on switch mode power supply based loads and utilizes the changes in the high frequency spectrum (e.g., 10 kHz (kilohertz)-500 kHz) due to the addition or removal of high frequency artifacts, which occur in every cycle (continuous). Triac based loads (such as dimmers) and other loads can produce very large broadband transients multiple times during each AC (alternating current) cycle as they abruptly turn on/off at a preset voltage. These transients can be 20-50 dB (decibels) larger than the signals of interest from switching supplies.
Accordingly, a need or potential for benefit exists for a device or method that can isolate weak signals in the presence of large amplitude signals.
For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. The same reference numerals in different figures denote the same elements.
The terms “first,” “second,” “third,” “fourth,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “include,” and “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, device, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, system, article, device, or apparatus.
The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.
The terms “couple,” “coupled,” “couples,” “coupling,” and the like should be broadly understood and refer to connecting two or more elements or signals, electrically, mechanically and/or otherwise. Two or more electrical elements may be electrically coupled but not be mechanically or otherwise coupled; two or more mechanical elements may be mechanically coupled, but not be electrically or otherwise coupled; two or more electrical elements may be mechanically coupled, but not be electrically or otherwise coupled. Coupling may be for any length of time, e.g., permanent or semi-permanent or only for an instant.
“Electrical coupling” and the like should be broadly understood and include coupling involving any electrical signal, whether a power signal, a data signal, and/or other types or combinations of electrical signals. “Mechanical coupling” and the like should be broadly understood and include mechanical coupling of all types.
The absence of the word “removably,” “removable,” and the like near the word “coupled,” and the like does not mean that the coupling, etc. in question is or is not removable.